When Dave Wittenberg began his acting career at a community theater in Boston, he never imagined that one day he’d be making his living as a voice artist for video game characters, portraying the likes of Hades, Tweedledee and Jerry Seinfeld.

But in the last decade Wittenberg’s voice has been heard in more video games than he “can remember.” And, though it’s not the traditional actor’s stagecraft, he still draws extensively on his thespian skills. “You get to create characters you wouldn’t be able to create in any other medium,” said Wittenberg, 38. “From an acting standpoint, it lets you flex your muscles that you wouldn’t ordinarily use.”

What it’s not doing, however, is fattening his wallet. Despite his extensive credits, Wittenberg earns roughly $30,000 a year from his video game work and, like most of his peers, supplements that income by doing voice work for animated TV shows.

Wittenberg is one of hundreds of Hollywood actors who perform in the heard-but-not-seen world of voice acting, breathing life into the virtual worlds of such blockbuster game franchises as Halo, Call of Duty and Grand Theft Auto.

The video game sector, once a backwater in Hollywood, has been the fastest-growing segment of the entertainment industry and increasingly competes with movies and television for consumers’ attention and dollars.

As games have become more like big-screen movies, so has their need for more sophisticated stories and emotionally engaging characters. Games once had practically no dialogue but now boast tens of thousands of lines of it -- creating opportunities for actors at time when traditional jobs are shrinking because of studios’ cutbacks in film and TV production.

But the enthusiasm for the new medium has been tempered by a growing unease among many performers that their pay for voice work in video games isn’t keeping pace with the industry’s breakneck growth. Although it’s down this year amid the recession, U.S. video game industry revenue has more than doubled since 2005 to $21 billion in 2008 -- about twice the amount of movie ticket sales in Canada and the U.S.

The concerns have fueled a standoff between the video gave companies and the Screen Actors Guild, whose members recently rejected a proposed contract that covers voice work in the video game industry. “The concern going forward is that as these games become larger and larger and generate more income, we as actors won’t see any more money when we walk out the door,” said Wittenberg.

Attorney Scott Witlin, who represented video game publishers in the recent labor negotiations, disputes the notion that actors are being shortchanged. “If you look at the total contribution either in terms of hours that go into the creation of a game or the earnings of the people who make the games, voice talent represents a minute percentage,” he said.

SAG’s bargaining clout is limited. The voices in about 80% of video game titles are performed by actors who don’t work under a guild contract. What’s more, SAG’s sister union, the American Federation of Television and Radio Artists, recently ratified a separate contract with video game publishers.

“It’s not so much their argument is weak or strong,” said Jonathan Handel, an adjunct professor at UCLA School of Law who specializes in entertainment labor law. “The overarching issue for any union making a deal is: Who has the leverage?”

There were practically no roles for actors in video games until the mid-1990s, when technical innovations made it possible to give speech to the digital characters. Video game cartridges before then had limited storage space, leaving little room for voice recordings. Dialogue instead appeared on the screen like subtitles on a foreign-language film.

“It used to be that there wasn’t very much data available for voice acting, and what we had tended to be cartoonish,” said Casey Hudson, director of the upcoming Electronic Arts game Mass Effect 2.

Later, with the advent of higher-capacity compact discs, characters started to speak a few dozen or hundred lines in games. But voices were still often performed by amateur actors or even the game developers themselves, because many companies didn’t think spoken dialogue was important enough to merit spending money on professionals.

In the last decade, however, as the video game industry has transitioned to DVDs and the storytelling ambitions of many game developers have blossomed, hiring experienced actors has become routine.

The use of actors in games varies broadly depending on the genre. Some titles include far more speech than a feature film. Mass Effect 2, a science-fiction game, has 90 actors playing 546 characters who speak about 31,000 lines of dialogue.

Uncharted 2, an adventure game recently released by Sony, intentionally mimics the cinematic style of movies like the “Indiana Jones” series. Actors not only performed voices but also acted in motion-capture suits for non-interactive story sequences -- called “cut scenes” -- that totaled about 90 minutes.

“We basically made a feature film at the same time that we made a game,” said Uncharted 2 director Amy Hennig, who worked with an experienced theater director to oversee acting. “Good performances are critical so that players maintain an empathetic association with the character who they control.”

Largely because of the industry’s roots in the software business, video game creators have traditionally been compensated very differently than creative workers in Hollywood. Unlike talent in movies and TV shows, they don’t receive residuals, or additional fees for the reuse of their work.

“In our business we’re all employees and any upside we get is purely discretionary, so many of us are not going to have a lot of sympathy for actors who want back-end residuals,” Hennig said. “That’s why we’re talking two different languages when we sit down at a bargaining table.”

The biggest sticking point in the dispute involves pay levels for a new category of actors: those who perform “atmospheric voices,” words and sounds for the incidental characters -- bartenders, soldiers, elves, random monsters -- in war and fantasy games that involve large crowds.

Under the proposed SAG contract, actors would receive a fee of about $800 for performing up to 20 atmospheric voices (up to 300 words per voice) in a four-hour session. Actors who perform “principal characters” -- defined as those that drive the story -- would fetch the same fee for doing up to three character voices, and more than double the amount if they do six to 10 voices during a six-hour session.

Although video companies offered a 2.5% increase in wages, an influential group of Hollywood voice actors has strongly opposed the contract. They contend that the provision would require them to do substantially more work for roughly the same pay and put undue stress on their vocal cords, notwithstanding a provision in the agreement to protect actors against “vocal stress.”

“Before, you were doing three characters dying a horrible death. Now you’re doing 20 characters dying a horrible death,” said Dee Baker, a veteran voice actor who has worked on such games as Halo 2 and Spore, in which he voiced entire races of evolving alien creatures. “Not only will this mean less money for more experiences, it’s also going to be a lot more vocally difficult.”

Though it seems counterintuitive, game developers say that advances in technology are making actors more important to the production process, not less.

Hudson, for instance, says he hopes that in the future, game makers will capture the facial expressions of actors for the eye and mouth movements of the animated characters whose voices they provide.

That’s one reason backers of the agreement -- including negotiators for both actors unions -- argue that the most important goal right now is to give the companies more incentive to hire union talent.

“One of the things we’d like to do is improve the union’s footprint in this area of production,” said Mathis Dunn Jr., an assistant national executive director of AFTRA. “A lot of employers are not signatories to our contract, and part of the reason is that we can’t accommodate their budget. . . . This will keep us in the game.”